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My Skater and new TU CNC 4 blade props

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Old 07-27-2009, 09:13 AM
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Location: Port Charlotte, FL
My Boats: CURR: 230LX, PREV:2007 30 Skater, 2003 36 Skater,1998 37 OuterLimits, B-Class race 28 Magnum
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Default My Skater and new TU CNC 4 blade props

What follows below, is my opinion, based on my testing. You should consult a professional, before attempting any of these tests or changes yourself.

This past weekend, I tried the Throttle Up CNC 14.75 x 31 4 blade props, on my boat, 30 Skater T/300XS. Compared to the 3 blade props they worked better at getting the boat on plane, quicker, easier, less vibration, they had better midrange acceleration, and wot performance, was 0.4mph faster. They do cause some additional stern lift, over 3 blade props, which makes the boat feels a bit looser, but it is manageable and water pressure is above 10lbs.

In total, we have tried 8 different propellers:
Merc Racing 14.5 x 32, 3 blade cleaver, lab finished
Merc Racing 14.5 x 34, 3 blade cleaver, lab finished
Merc Racing 15 x 32, 3 blade cleaver, double lab finished
Merc Racing 15 x 32, 3 blade cleaver, lab finished
Throttle-Up CNC 15 x 30, 5 blade, cleaver
Throttle-Up CNC 14.75 x 30, 5 blade, cleaver
Throttle-Up CNC 15 x 31, 4 blade, cleaver
Throttle-Up CNC 14.75 x 31, 4 blade cleaver

We have also tried 8 different setups:
Props turning in
Props turning out
Prop shaft height, 7/8 above bottom
Prop shaft height, 1 1/2 above bottom
Prop shaft height, 1 5/8 above bottom
Prop shaft height, 1 3/4 above bottom
Toe out 1/4
Toe 0

The best setup is, 1 3/4 above the bottom, toe 0, props turning in, and a bottom modification “water ramps” to get the necessary water pressure.

The 5 blade props just have way to much stern lift for my boat, which leave the best 3 blade and the best 4 blade prop. They are the MR 15 x 32, 3 blade cleaver, lab finish, and the TU CNC 14.75 x 31, 4 blade, cleaver.

Here are the back to back runs for the 2 best props:

Weather underground, NOAA, National Weather Service, and Weather Channel, reported the following at the time of my runs:
Air temperature low/mid 90s
Humidity 67% - 90%
Heat index 105-110

MR 15 x 32, 3 blade cleaver lab
TU CNC 14.75 x 31, 4 blade cleaver

PORT STBD AVG MPH SLIP
MR 5837 6005 5921 97.3 9.32%
MR 6025 5909 5937 97.9 9.46%
MR 5994 6009 6002 99.7 8.32%

TU 6029 6216 6213 99.2 10.59%
TU 6042 6257 6150 99.4 10.80%
TU 6072 6261 6186 100.1 10.44%

I scored each prop in 4 categories; getting on plane, mid range acceleration, wot speed, and handling, giving 1 point to the prop that won each category. The final score

3 points = TU CNC 14.75 x 31, 4 blade, cleaver
1 points = MR 15 x 32, 3 blade cleaver, lab finish

For me, the Throttle-Up CNC 14.75 x 31, 4 blade cleaver, are my propellers of choice and will remain on my boat.
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